Share your experience!
Did you check using sony update service or pc companion?
http://www.sonymobile.com/gb/tools/update-service/ - SUS
http://www.sonymobile.com/gb/tools/pc-companion/ - PCC
ICS is a big update,it is not necessarily that you get a notification on your phone.Try those programs I have told you.
Look, About the ICS 4.0.4, You Install PC Companion in your PC and Plug your Xperia U using USB Cable and PCC will automaticlly Check for an update. you Won't see the update in your phone because ICS is a Huge update, so it's only can be upgraded using a PC
However, i have ICS, i Wish you hear my Word and DO NOT install ICS update.
Belive me you won't love it Much lag much bugs...
First Bug making me sad about ICS is Camera. it's Lagging as **bleep** indoors, Plus, Sooooooooo Much Noise.
you feel like you are capturing using a cheap chinese Webcam
however outdoors it remined the same.
Lags alot, i have only the necessary apps liek Viber, Whatsapp,Skype, etc.
This is Due to Small RAM and High ICS Usage..
Sometimes it's fast
Sometimes it dies, Even the Keyboard Lags as **bleep**
If you had a Clean install, With Only Essential Apps, You won't be able to Run Chrome with a Music, One of the things will die, Music or Chrome or Keyboard..
am i using an Mp3 or "smart" Phone??
i wish you to don't upgrade.
Have a good day 
Hi.
I've installe ICS update, but it doesn't work fine.
Does somebody know how to downgrade to 2.3.7 (original) version?
Is there any oficial way to do it? (I mean no rooting ...)
Thanks.